Posttraumatic Stress Disorder (PTSD) and its long-term sequelae are recognized as a major burden for Vietnam combat veterans and survivors of atrocities or disasters. However, the disorder, as defined in DSM-III-R, can occur also in response to traumatic events experienced by individuals in the general population. The high rates of violent crimes and injuries in USA communities constitute a strong rationale for research on traumatic events and PTSD in the community. In a study of 1007 randomly selected young adults, conducted in 1989, we found that 39% had experienced in their lifetime one or more events that qualify for the DSM-III-R PTSD stressor criterion, and that 23.6% of those exposed met criteria for PTSD. PTSD was associated with increased rates of other psychiatric and psychoactive substance use disorders, use of health care for mental health problems and functional impairment. Predisposing factors for exposure to traumatic events and for PTSD following exposure were identified. We propose to conduct follow-up interviews in the third and fifth year after baseline to examine the long-term consequences of PTSD and exposure to traumatic events, in terms of functional impairment, psychiatric comorbidity, the occurrence of PTSD after a new exposure, and the lag time between PTSD and the onset of later disorders. In addition, using data on socially desirable responding and from medical records, to be obtained in follow-up, we propose to test the associations of PTSD with other disorders and with use of health care, under conditions that minimize the potential bias when all the data are from self-reports. The data analysis plan is designed to test hypotheses about the degree to which change in dependent variables during follow-up depends upon factors measured at baseline. Multivariate analysis with covariates, primarily multiple logistic regression and proportional hazards models, will be used.